Laser Induced Breakdown Spectroscopy (LIBS), also known as Laser Induced Plasma Spectroscopy (LIPS), is a method used for quick analysis of a sample's elementary constituents. LIBS is based on the analysis of the spectrum of light emitted by the atoms of a sample, when they are excited and ionized by a high power, short laser pulse (usually in the nanosecond range) focused on a target sample surface. A volume of the sample is vaporized and ionized to produce a plasma or spark having an elemental composition representative of the sample. The plasma, characteristic of elements present in the sample, are then collected and analyzed with a spectrometer to obtain an atomic composition. LIBS provides a fast and direct method of elemental analysis and even very small amounts (in low parts-per-million range) of an element can be detected in real time.
A number of methods have been applied to address the need for instantaneous evaluation of mineral contents on moving belt systems. There remains a need, however, for a method of analyzing the surface of a heterogeneous solid having three-dimensional substance(s) or coating(s) adhered thereto and having variable heights. There is also a need for an efficient and accurate method of on-line/real-time analysis of cooked food products having seasoning(s) or other coating(s) thereon. In particular, the method should overcome the difficulties associated with the inert properties of salt and other elements, which makes accuracy of on-line detection historically unobtainable in food applications. Such method should be reliable and cost-effective while providing for nearly instantaneous monitoring and feedback control of the food products and without negatively influencing product integrity (i.e., flavor, stability and quality). For example, such method should allow for quality control of food products prior to being packaged for consumption.